Higher fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) uptake in tuberculous compared to bacterial spondylodiscitis

Background: Tuberculous spondylodiscitis can be difficult to diagnose because of its nonspecific symptoms and the similarities with non-tubercular forms of spinal infection. Fluorine-18-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG PET-CT) is increasingly used for the diagnosis and monitoring of tubercular diseases. Methods: Retrospective, case-control study comparing tuberculous spondylodiscitis with biopsy-confirmed pyogenic spondylodiscitis in the period 2010–2012. Results: Ten cases of tuberculous spondylodiscitis and 20 controls were included. Compared to pyogenic, tuberculous spondylodiscitis was more frequent in younger patients (P = 0.01) and was more often associated with thoraco-lumbar tract lesions (P = 0.01) and multiple vertebral involvement (P = 0.01). Significantly higher maximum standardized uptake values (SUV) at FDG-PET were displayed by tuberculous spondylodiscitis compared to controls (12.4 vs. 7.3, P = 0.003). SUV levels above 8 showed the highest value of specificity (0.80). Mean SUV reduction of 48% was detected for tuberculous spondylodiscitis at 1-month follow-up. Conclusions: Higher SUV levels at FDG-PET were detected in tuberculous compared with pyogenic spondylodiscitis. PET-CT use appeared useful in the disease follow-up after treatment initiation.